The invention relates to fasteners or anchors and, more particularly, to fasteners or anchors for securement into biological tissue, particularly bone. The invention finds particular application in the securement of sutures to bone, such as the attachment of torn ligaments or ligament replacements to the bone through attachment of the suture to the anchor.
In the medical field, it is frequently necessary to securely attach elements such as ligaments (e.g. rotator cuff ligaments, anterior cruciate ligaments) and prosthetics, to a bone. Such attachment requires, initially, that an anchor be secured within the bone itself. Once the anchor is secured, the ligament or prosthetic can be attached to the anchor through, for example, sutures extending from the anchor.
Various techniques exist for securing an anchor within a bone. In co-pending U.S. application Ser. No. 08/470,988 now U.S. Pat. No. 5,792,165 assigned Li Medical Technologies, Inc., for example, a longitudinally extending groove is first drilled within the bone. An anchor disposed perpendicularly to an insertion handle, is then inserted into the groove and screwed into the bone until the anchor is held securely therein. Since the anchor is disposed perpendicularly to the handle, it is necessary to prepare a groove large enough to accommodate the size of the anchor including its entire length.
Bones are made of a relatively hard outer layer of tissue made of cortical bone cells and a softer inner layer of tissue made of cancellous cells. By making such grooves in the bone, a larger amount of the harder cortical bone cells must be removed thereby decreasing the affixment strength available for securing the anchor within the bone.
In co-pending U.S. application Ser. No. 09/088,572 now U.S. Pat. No. 6,102,934 also assigned to Li Medical Technologies, Inc., a rotor blade inserter includes a pushing member having a cam surface thereon that engages with an anchor. The pushing member slides in a channel. A collar is disposed on and threaded with the handle. When the collar is rotated, the collar traverses along the handle, transferring the translational motion to the pushing member, which in turn produces a rotational movement of the anchor through the engagement of the anchor with the cam surface. In order to insert the anchor into a bone, a user must rotate a handle of the device and also manipulate the collar. This operation can be quite cumbersome and difficult to effectuate. An embodiment is disclosed where a spring trigger can be used to apply a force upon the pushing channel when the spring trigger is actuated. However, actuation of the trigger is an additional manipulation which must be performed. In many surgical applications, a surgeon""s hands are occupied by numerous tasks and so it is important to provide a device which can be actuated with as few movements as possible and/or with one hand.
In U.S. Pat. No. 5,203,787 to Noblitt et al., a hole is drilled in a bone and then an anchoring device is inserted into the hole so that a longitudinal axis of the anchoring device is parallel to a longitudinal axis of the hole. A force is then applied to a suture coupled to the anchoring device thereby causing the anchoring device to rotate within the cancellous cells of the bone so that the anchor extends perpendicularly to the longitudinal axis of the hole. The anchor is then held within the bone by abutting against the inside of the harder cortical bone cells. The technique of Noblitt et al., however, requires complex manipulation of the suture to achieve the desired orientation of the anchor.
Moreover, modem trends in surgery include the restoration of bodily function and form, or repair of anatomical structures through the use of minimally invasive surgical techniques. The ability to surgically repair damaged tissues or joints creating as few and as small incisions as possible, and with ease of manipulation, produces less trauma to the patient, less pain and generally better clinical outcomes.
Thus, there exists a need in the art for a minimally invasive method and device which more securely attaches an anchor within a bone than devices and techniques of the prior art.
One aspect of the invention is a method for securing an anchor to biological tissue, the anchor being detachably and pivotably mounted to an insertion tool, the anchor having a longitudinal axis, the insertion tool having a first axis that extends longitudinally with respect to the insertion tool, and a second axis which extends perpendicularly to the first axis. The method comprises the steps of holding the anchor with the insertion tool; and applying a biasing force to the anchor to bias the anchor toward a position that is substantially perpendicular to the first axis. The method further comprises the steps of inserting the anchor held by the insertion tool, with the longitudinal axis of the anchor being disposed in an orientation that is not perpendicular to the first axis, into a borehole in the biological tissue; and rotating the anchor about the first axis, the biasing force causing the anchor to engage with a sidewall of the bore hole and to penetrate into the sidewall. In this way, the anchor is screwed into the object as the insertion tool is rotated about the first axis until the anchor achieves an orientation substantially perpendicular to the first axis.
Another aspect of the invention is a tool for securing an anchor to biological tissue. The tool comprises a handle, the handle having a first axis that extends longitudinally with respect to the handle, and a second axis that extends perpendicularly to the first axis; an anchor pivotably coupled to the handle so that the anchor is pivotable about the second axis; and a biasing member disposed in or on the handle, the biasing member biasing the anchor toward a position which is substantially perpendicular to the first axis. The handle being rotatable about the first axis to allow the anchor to rotate about the first axis, the biasing member causing the anchor to penetrate into a bore hole in the biological tissue by pivoting about the second axis, and to screw into the bore hole to attain a position which is substantially perpendicular to the first axis when the anchor is inserted into the bore hole in the biological tissue.
Yet another aspect of the invention is a tool for securing an anchor to biological tissue. The tool comprising a handle, the handle having a first axis that extends longitudinally with respect to the handle, and a second axis that extends perpendicularly to the first axis; an anchor pivotably coupled to the handle so that the anchor is pivotable about the second axis; and a biasing member disposed on the handle, the biasing member biasing the anchor toward a position which is substantially perpendicular to the first axis.
These aspects, as well as others, will become apparent upon reading the following disclosure and corresponding drawings.